Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Configuring a System
Reconfiguring the Kernel (HP-UX 11i Version 2)
Chapter 3 335
System administrators can create their own “user-defined” tunables if
they choose. These will not affect the operation of the system directly, but
they can be used in computing the values of other tunables. For example,
an administrator could choose to create a num_databases tunable, and
then set several kernel tunables based on its value. A subsequent change
to the value of num_databases would cause all of the related kernel
tunable values to be changed as well.
Getting Information About Tunables
When you run kctune with no options, it shows you the tunables
associated with the kernel modules on your system (as well as any
user-defined tunables), their current values, and the expressions used to
compute those values. If there are changes to those values being held for
next boot, those will be shown as well. On a typical system, the
expression for most tunables is “Default”, meaning that the
administrator is allowing the system to choose the tunable value.
When you use the -c (configuration) option, kctune displays the tunable
information from a saved configuration instead of the currently running
system.
The output of kctune can be varied with several options. To control
which tunables are listed, use the -D (Differences) or -S (Set) option. The
-D option restricts the output to only those tunables whose value at next
boot is different from their current value. The -S option restricts the
output to only those tunables that are set to a nondefault value. The
output can also be restricted by listing tunable names on the command
line.
To control the output format, use the -d (description), -g (group), -v
(verbose), or -P (Parse) option. Without these options, the output looks
like this:
Tunable Current Expression Changes
acctresume 4 Default
maxuprc 256 Default Immed
nproc 4200 Default Immed
The -d option adds the description of each tunable:
Tunable Current Expression Changes
Description
acctresume 4 Default
Percentage of disk space that must be free to resume accounting
maxuprc 256 Default Immed